The invention relates to influencing the nervous system of a subject by pulsative stimulation of sensory receptors, relying on the mechanisms of sensory resonance and frequency modulation of spontaneous spike patterns, as discussed in U.S. Pat. No. 5,782,874. [1]. In that patent, the stimulation is provided by an external electric field applied to the skin of the subject. The electric field appears to cause a modulation of the spiking patterns of certain cutaneous receptors, so that a pulsative field gives rise to a frequency modulation (fm) of the produced spike trains. Afferent nerves carry the frequency modulated spike trains to the brain, where in certain neural circuits the evoked fm signals cause excitation of a resonance with observable physiological consequences. One such "sensory resonance" that occurs near 1/2 Hz causes sleepiness, relaxation, a tonic smile, ptosis of the eyelids, a tense feeling in the stomach, or sexual excitement, depending on the precise pulse frequency used. The 1/2 Hz sensory resonance can also be excited by magnetic fields, as discussed in U.S. Pat. No. 5,935,054 [2].
Another known sensory resonance occurs near 2.4 Hz and causes a slowing of certain cortical activities.